One such process is known from WO 2005/044968. A large number of cleaning processes are described in that publication, all of which work with a cleaning-, disinfection-, and indicator agent based upon a permanganate, particularly potassium permanganate, in an alkali environment. This agent is available on the commercial market, and has also been described in EP 1 343 864, for example. The cleaning-, disinfection-, and indicator agent that is used contains, apart from the water-soluble permanganate, an additional oxidation agent, the oxidation potential of which lies above that of Mn VII to Mn VI. The acidic environment can already be adjusted in the product sold, but is, however, preferably adjusted by the client by mixing with an alkaline agent, whereby the pH value should preferably amount to at least twelve. In the latter case, the cleaning-, disinfection-, and indicator agent additionally contains pH buffer substances, preferably primary and/or secondary alkali carbonates, such as sodium carbonate and/or sodium hydrogen carbonate, for example, as well as oxidation-resistant polyphosphates. In the compound described, permanganate, particularly potassium permanganate, can be used as a very effective cleaning agent with a disinfecting effect. Since potassium permanganate, depending on the level of contaminants contained, shows changes in color from an initial violet to green and yellow when flowing through the installation to be cleaned, the known agent can also be used as an indicator solution in order to test the level of cleaning. If the fluid circulating in the installation remains violet after the addition of the potassium permanganate, then the installation has been sufficiently cleaned. A change in color to green, and particularly to yellow, however, indicates that the installation has only been incompletely cleaned or is not yet clean, as the case may be. Upon use as a cleaning agent, the known agent can be used in a so-called stack-type cleaning—that is to say, it is collected after passing through the installation and, after refreshing, if necessary, it is used again in the next cleaning process. The indicator is then no longer fully usable during the next cleaning process, however, since it has, in fact, already been partially used up. A good evaluation of the success of the cleaning is then no longer possible to an unlimited extent, since the cleaning fluid has the characteristic of reacting more sensitively during color changes when in its basic condition (that is to say, from purple to green and yellow, for example) than it does during color changes in an already slightly-used condition (that is to say, from green to yellow, for example). In order to be able to carry out an optimal cleaning test in the previous stack-type cleaning, an expensive new formulation of the solution must therefore be carried out after every cleaning. In the known process, the agent must be discarded upon use as a (sole) indicator agent.